Exhaust gas temperature sensor with anti-resonance finned shaft feature

ABSTRACT

A sensor assembly including a sensing element, a conductor connected to the sensing element, and an elongated shaft. The elongated shaft includes a proximal end, a distal end, an inner surface, an outer surface, and a plurality of spaced apart vibration dampers. The inner surface defines a throughbore extending from the proximal end to the distal end. The throughbore is configured to receive the conductor therethrough. The vibration dampers protrude from the outer surface and extend from the proximal end towards the distal end.

FIELD

The present disclosure relates to an exhaust gas temperature sensor withan anti-resonance finned shaft feature.

BACKGROUND

This section provides background information related to the presentdisclosure, which is not necessarily prior art.

Motor vehicles often include an exhaust gas temperature sensor formeasuring the temperature of an exhaust gas stream emitted from thevehicle. The sensor often includes a temperature sensing element mountedat a distal end of an elongated shaft of the sensor. The elongated shaftsupports the sensing element in the exhaust gas stream in order to sensethe temperature thereof. The further the sensing element is positionedinto the exhaust gas stream, generally the more accurate the temperaturereading will be. It is thus advantageous to have a shaft with anextended length in order to position the sensing element as far into theexhaust gas stream as possible. However, shafts having an extendedlength are often subject to excessive vibrations transferred theretofrom the engine. For example, a typical vehicle engine may vibrate atbetween 250 Hz and 400 Hz. An elongated sensor shaft of 80 millimetershaving a uniform outer diameter of 3 millimeters will often begin tovibrate at about 393 Hz, and will thus experience excessive vibrationduring normal engine operation, which may lead to temperature readingsof decreased accuracy and/or damage to the sensor. An exhaust gastemperature sensor having an elongated shaft for supporting atemperature sensing element in an exhaust gas stream that is not subjectto extensive vibration during standard operation of a typical engine ormotor would thus be desirable.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for a sensor assembly including a sensingelement, a conductor connected to the sensing element, and an elongatedshaft. The elongated shaft includes a proximal end, a distal end, aninner surface, an outer surface, and a plurality of spaced apartvibration dampers. The inner surface defines a throughbore extendingfrom the proximal end to the distal end. The throughbore is configuredto receive the conductor therethrough. The vibration dampers protrudefrom the outer surface and extend from the proximal end towards thedistal end.

The present teachings also provide for a sensor assembly including asensing element, a conductor connected to the sensing element, and anelongated shaft. The elongated shaft includes a proximal end, a distalend, an inner surface, an outer surface, and a plurality of evenlyspaced apart vibration dampers. The inner surface defines a throughboreextending from the proximal end to the distal end. The throughboreconfigured to receive the conductor therethrough. The vibration dampersprotrude from the outer surface, extend from the proximal end towardsthe distal end, and terminate prior to reaching the distal end. Thevibration dampers extend generally parallel to a longitudinal axis ofthe elongated shaft. The sensing element is configured to senseproperties of a gas.

The present teachings further provide for a sensor assembly including atemperature sensing element, a conductor connected to the temperaturesensing element, and an elongated shaft. The elongated shaft includes aproximal end, a distal end, an outer surface, and an inner surfacedefining a throughbore extending from the proximal end to the distalend. The throughbore is configured to receive the conductortherethrough. One of four or six vibration dampening ribs protrude fromthe outer surface and are evenly spaced apart radially about alongitudinal axis of the elongated shaft, and extend from the proximalend parallel to the longitudinal axis across a mid-point of theelongated shaft. The ribs terminate prior to reaching the distal end.The temperature sensing element is an exhaust gas temperature sensingthermistor.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a cross-sectional view of an exhaust gas temperature sensorassembly according to the present teachings;

FIG. 2A is a perspective view of an elongated shaft for use with thesensor assembly of FIG. 1;

FIG. 2B is a cross-sectional view taken along line 2B-2B of FIG. 2A;

FIG. 2C is a cross-sectional view taken along line 2C-2C of FIG. 2A;

FIG. 3A is a perspective view of another elongated shaft for use withthe sensor assembly of FIG. 1;

FIG. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A;

FIG. 3C is a cross-sectional view taken along line 3C-3C of FIG. 3A;

FIG. 4A is a perspective view of an additional elongated shaft for usewith the sensor assembly of FIG. 1;

FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A;

FIG. 4C is a cross-sectional view taken along line 4C-4C of FIG. 4A;

FIG. 5A is a perspective view of still another elongated shaft for usewith the sensor assembly of FIG. 1;

FIG. 5B is a cross-sectional view taken along line 5B-5B of FIG. 5A;

FIG. 5C is a cross-sectional view taken along line 5C-5C of FIG. 5A; and

FIG. 6 is an additional elongated shaft for use with the sensor assemblyof FIG. 1.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With initial reference to FIG. 1, a sensor assembly according to thepresent teachings is generally illustrated at reference numeral 10. Thesensor assembly 10 can be configured to sense any suitable parameter inany suitable application. For example, the sensor assembly 10 can beconfigured to sense one or more of temperature; pressure; constituentcomponents, such as of a gas; chemical composition; etc. The sensorassembly 10 can be any suitable temperature sensor assembly, such as anexhaust gas temperature sensor assembly. For example, the sensorassembly 10 can be a motor vehicle exhaust gas temperature sensorassembly, the motor vehicle being any suitable motor vehicle, such as anautomobile, a truck, an aircraft, a military vehicle, or a watercraft,for example. The sensor assembly 10 can also be used in conjunction withan engine not associated with a vehicle, such as a generator, an HVACsystem, or any type of machinery or equipment.

In the exemplary illustration of FIG. 1, the sensor assembly 10 includesa housing 12, a coupling member 14, an elongated shaft 16, conductors18, and a temperature sensing element 20. The housing 12 can be anysuitable housing, such as a generally cylindrical housing configured toreceive the coupling member 14 and the elongated shaft 16 within adistal end 22 of the housing 12. The housing 12 can include any suitablelocking member for securing the coupling member 14 therein, such ashousing locking members 24. The housing locking members 24 are generallyillustrated as teeth mounted to an interior of the housing 12, whichextend inward to grip a portion of the coupling member 14 seated withinthe housing 12 at the distal end 22 thereof.

The coupling member 14 defines a through-bore through which theelongated shaft 16 extends into the housing 12. The coupling member 14includes coupling member locking members 26, which secure the elongatedshaft 16 to and within the coupling member 14. The locking members 26can be any suitable locking members or device to secure the elongatedshaft 16 to and within the coupling member 14, such as teeth that extendinto the bore defined by the coupling member 14 as generallyillustrated.

The conductors 18 extend through at least a portion of the housing 12and into the elongated shaft 16 at a proximal end 28 of the elongatedshaft 16, which is seated within the housing 12. The conductors 18extend entirely through the elongated shaft 16, and exit the elongatedshaft 16 at a distal end 30 thereof, which is opposite to the proximalend 28. The conductors 18 can be any suitable type of electricalconductor, such as wire leads.

The temperature sensing element 20 is coupled to the conductors 18 at aportion thereof extending beyond the distal end 30. The temperaturesensing element 20 can be any suitable element or device suitable forsensing temperature, such as a temperature of exhaust gas emitted from avehicle engine, such as an internal combustion engine. The temperaturesensing element 20 can thus be a thermistor element, for example. Thetemperature sensing element 20 and portions of the conductors 18extending from the distal end 30 of the elongated shaft 16 can becovered by a cap 32. The cap 32 can be any suitable cap, such as toprotect the temperature sensing element 20 and the conductors 18proximate thereto. The cap 32 can be secured in any suitable manner,such as with a press fit at the distal end 30 in which the distal end 30extends within the cap 32.

The elongated shaft 16 can be provided in a variety of different formsand can include a variety of different features in order to dampenvibration thereof, and thus isolate the elongated shaft 16 and thetemperature sensing element 20 from vibrations generated by an engine ofa vehicle or machine that the sensor assembly 10 is associated with.Various exemplary elongated shafts are illustrated in FIGS. 2A-6, and atreference numbers 16 a-16 e. The elongated shafts 16 a-16 e will now bedescribed in detail.

Each one of the elongated shafts 16 a-16 e generally includes a proximalend 110 and a distal end 112, which is opposite to the proximal end 110.The proximal end 110 corresponds to the proximal end 28 of FIG. 1, andthe distal end 112 corresponds to the distal end 30 of FIG. 1. Each oneof the elongated shafts 16 a-16 e can have any suitable length, such as80 mm or about 80 mm. Each one of the elongated shafts 16 a-16 e canhave any suitable diameter. For example, each one of the elongatedshafts 16 a-16 e can have a maximum outer diameter of 3 mm or about 3 mmat the distal end 112, and a maximum outer diameter of 4.5 mm or about4.5 mm at the proximal end 110. The elongated shafts 16 a-16 e can bemade of any suitable material, such as stainless steel. Any suitabletype of stainless steel can be used, such as SUS 310S including, forexample, a density of 8,000 kilograms per meters cubed, a Young'smodulus of 2×10⁵ MPa, a Poison's ratio of 0.3, and material damping of0.5%.

Each one of the elongated shafts 16 a-16 e also includes an innersurface 114 and an outer surface 116 opposite thereto. The inner surface114 defines a through-bore 118, which extends from the proximal end 110to the distal end 112. The through-bore 118 extends along a longitudinalaxis A of each one of the elongated shafts 16 a-16 e. The longitudinalaxis A extends along a length of each one of the elongated shafts fromthe proximal end 110 to the distal end 112. The longitudinal axis Agenerally extends through an axial center of the through-bore 118.

With particular reference to FIGS. 2A-2C, the elongated shaft 16 aincludes a plurality of vibration dampers, which as illustratedgenerally take the form of a first rib 120 a, a second rib 120 b, athird rib 120 c, and a fourth rib 120 d. All four of the ribs 120 a-120d are illustrated in the cross-sectional view of FIG. 2B. Each one ofthe ribs 120 a-120 d includes a proximal rib end 122 a-122 drespectively, and a distal rib end 124 a-124 d respectively. Each one ofthe ribs 120 a-120 d protrude beyond the outer surface 116. Each one ofthe ribs 120 a-120 d extend generally parallel to the longitudinal axisA from at or proximate to the proximal end 110 of the elongated shaft 16a towards the distal end 112 thereof.

The ribs 120 a-120 d can extend parallel to the longitudinal axis A toany suitable position along the length of the elongated shaft 16 a, suchas to a midpoint B of the elongated shaft 16 a, which is equidistantbetween the proximal end 110 and the distal end 112. The ribs 120 a-120d can terminate prior to reaching the midpoint B, such that the distalrib ends 124 a-124 d are on a proximal side of the midpoint B and thuscloser to the proximal end 110 than the distal end 112. The ribs 120a-120 d can also extend beyond the midpoint B as illustrated, such thatthe distal rib ends 124 a-124 d are closer to the distal end 112 thanthe proximal end 110. As illustrated, the distal rib ends 124 a-124 cextend across two-thirds, or approximately two-thirds, of the length ofthe elongated shaft 16 a, as measured from the proximal end 110.

Each of the ribs 120 a-120 d can include a tapered portion 126 a-126 drespectively at the distal rib ends 124 a-124 d thereof. The taperedportions 126 a-126 d generally provide a transition between the ribs 120a-120 d and the outer surface 116 at the distal rib ends 124 a-124 d.The ribs 120 a-120 d are spaced apart about the outer surface 116 andthe longitudinal axis A. The ribs 120 a-120 d can be uniformly spacedapart at regular intervals, or can be spaced apart at any other suitableuniform or non-uniform intervals. At the proximal end 110, the elongatedshaft 16 a can have a maximum outer diameter as measured across opposingones of the ribs 120, such as first rib 120 a and third rib 120 c, of4.5 millimeters, or about 4.5 millimeters. At the distal end 112, theelongated shaft 16 a can have a maximum outer diameter as measuredacross the longitudinal axis A of about 3.0 millimeters. The ribs 120a-120 f can be monolithic with the remainder of the elongated shafts 16c or 16 d. The ribs 120 a-120 f can also be integral with the outersurface 116 or can be mounted thereto in any suitable manner, such aswith a suitable adhesive or mechanical connection.

Although four ribs 120 a-120 d are illustrated in FIGS. 2A-2C inconjunction with the description of the elongated shaft 16 a, anysuitable number of ribs 120 can be provided. For example and withadditional reference to FIGS. 3A and 3B, six ribs 120 a-120 f can beprovided. The ribs 120 a-120 f can be evenly spaced apart about theelongated shaft 16 b as illustrated, or can be provided at any suitableregular or irregular interval. Any suitable number of the ribs 120 canbe provided in addition to the four ribs 120 a-120 d of FIGS. 2A and 2B,and the six ribs 120 a-120 f of FIGS. 3A and 3B. For example, three,five, seven, eight, nine, ten, etc. ribs 120 can be provided.

With additional reference to FIGS. 4A-4C, the elongated shaft 16 c isillustrated. The elongated shaft 16 c includes numerous features incommon with the elongated shafts 16 a and 16 b, and thus the similarfeatures are referenced with like reference numerals in the figures, andthe descriptions of these like features set forth above also apply tothe elongated shaft 16 c. The outer surface 116 of the elongated shaft16 c is tapered inward towards the longitudinal axis A between theproximal end 110 and line D proximate to the distal end 112. Betweenline D and the distal end 112 the outer surface 116 is not tapered.Alternatively, the entire length of the outer surface 116 can betapered.

The outer surface 116 can have a constant and continuous taper betweenthe proximal end 110 and the line D, such that angle alpha (α) measuredbetween the outer surface 116 (lines C illustrated in FIG. 4A areextensions of the outer surface 116) and the longitudinal axis A is thesame along the length of the elongated shaft 16 c between line D and theproximal end. The outer surface 116 need not be tapered consistently,however. The outer surface 116 can be generally smooth along its entirelength, or at any suitable portions or intervals thereof. The innersurface 114 may have a constant diameter as illustrated, or may betapered inward towards the longitudinal axis A from the proximal end 110to the distal end 112, or from the proximal end 110 to the line D. Theelongated shaft 16 c can have a maximum outer diameter at the proximalend 110 as measured perpendicular to the longitudinal axis A of about4.5 millimeters, and an outer diameter as measured perpendicular to thelongitudinal axis A at the distal end 112 of about 3.0 millimeters.

With reference to FIGS. 5A-5C, the elongated shaft 16 d is illustrated.The elongated shaft 16 d includes numerous features in common with theother elongated shafts 16 a, 16 b, 16 c, and 16 e, and thus the similarfeatures are referenced with like reference numerals in the figures, andthe descriptions of these like features also apply to the elongatedshaft 16 d. The elongated shaft 16 d generally includes three sections,portions, or lengths: a proximal length Lp, a distal length Ld, and amid-length Lm.

The proximal length Lp extends from the proximal end 110 to line E,which is between the mid-point B of the length of the elongated shaft 16d and the proximal end 110. The distal length Ld extends from the distalend 112 to line D. The mid-length extends between lines D and E, andacross the mid-point B. The lengths Lp, Lm, and Ld can be any suitablelength. Along the proximal length Lp, the maximum outer diameter of theelongated shaft 16 d remains constant, such as at a maximum outerdiameter of 4.5 mm or about 4.5 mm. Along the distal length, the maximumouter diameter of the elongated shaft 16 d also remains constant, suchas at a maximum outer diameter of 3.0 mm or about 3.0 mm. Along themid-length Lm, the elongated shaft 16 d is tapered inward towards thelongitudinal axis A from the proximal end 110 to the distal end 112. Theouter surface 116 thus tapers inward from a maximum outer diameter of4.5 mm or about 4.5 mm at line E, to a maximum outer diameter of 3.0 mmor about 3.0 mm at line D. The outer surface 116 can taper at a constantrate along its length, or any suitable rate. The inner surface 114 canbe tapered, or can have a constant maximum inner diameter along theentire length of the mid-length Lm.

With reference to FIG. 6, the elongated shaft 16 e is illustrated. Theelongated shaft 16 e includes a plurality of lengths, sections, orsegments 150 a-150 d, each of which has a different maximum outerdiameter at the outer surface 116. For example, a first segment orproximal segment 150 a is at the proximal end 110. A second segment 150b is adjacent to the first segment 150 a and extends from the firstsegment 150 a towards the distal end 112. A third segment 150 c isadjacent to the second segment 150 b and extends from the second segment150 b towards the distal end 112. A fourth segment 150 d is adjacent tothe third segment 150 c and extends from the third segment 150 c to thedistal end 112.

The first segment 150 a includes an outer surface 116 c. The secondsegment 150 b includes an outer surface 116 d. The third segment 150 cincludes outer surface 116 e. The fourth segment 150 d includes outersurface 116 f. The outer surface 116 c has the greatest outer diameteras compared to the outer surfaces 116 d, 116 e, and 116 f. The outersurface 116 d has an outer diameter that is smaller than that of theouter surface 116 c, and greater than the outer diameter of each of theouter surfaces 116 e and 116 f. The outer surface 116 e has an outerdiameter that is smaller than that of each of the outer surfaces 116 cand 116 d, and greater than the outer diameter of the outer surface 116f. The outer surface 116 f has the smallest outer diameter, which issmaller than the outer diameter of each of the outer surfaces 116 c-116e.

Between each of the segments 150 a-150 d is a stepped portion where theouter diameter of the outer surface 116 changes. Specifically, a firststep 152A is between the first segment 150 a and the second segment 150b. A second step 152B is between the second segment 150 b and the thirdsegment 150 c. A third step 152C is between the third segment 150 c andthe fourth segment 150 d. Each of the first, second, third, and fourthsegments 150 a-150 d have a uniform diameter along their lengths attheir respective outer surfaces 116 c-116 f. Each of the first throughfourth segments 150 a-150 d can have a similar length, such as 80millimeters, or about 80 millimeters, or can have different lengths.Furthermore, some of the segments 150 a-150 d can have the same length,while others have different lengths. The segments 150 a-150 d can haveany suitable length, such as 20 millimeters each, or about 20millimeters each.

The outer diameter of each one of the first through fourth segments 150a-150 d can each be of any suitable dimension. For example, the firstsegment 150 a can have an outer diameter at the outer surface 116 c of4.5 millimeters, or about 4.5 millimeters. The second, third, and fourthsegments 150 b-150 d can have progressively smaller outer diameters andcan decrease at any suitable interval, such as 0.5 millimeters or about0.5 millimeters. Therefore, the second segment 150 b can have an outerdiameter of 4.0 millimeters, or about 4.0 millimeters at outer surface116 d. The third segment 150 c can have an outer diameter of 3.5millimeters, or about 3.5 millimeters, at the outer surface 116 e. Thefourth segment 150 d can have an outer diameter of 3.0 millimeters, orabout 3.0 millimeters, at the outer surface 116 f. Although foursegments 150 a-150 d are illustrated, any suitable number of segments150 can be provided, such as only two, only three, only four, only five,only six, only seven, or only eight, for example.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A sensor assembly including a sensing element, aconductor connected to the sensing element, and an elongated shaftcomprising: a proximal end; a distal end; an inner surface defining athroughbore extending from the proximal end to the distal end, thethroughbore configured to receive the conductor therethrough; an outersurface; and a plurality of spaced apart vibration dampers protrudingfrom the outer surface and extending from the proximal end towards thedistal end; wherein each one of the vibration dampers extends linearlyand parallel to a longitudinal axis of the elongated shaft.
 2. Thesensor assembly of claim 1, wherein the sensing element is a temperaturesensing thermistor and the conductor is configured to support thethermistor spaced apart from the elongated shaft at the distal end. 3.The sensor assembly of claim 1, wherein the elongated shaft includesstainless steel.
 4. The sensor assembly of claim 1, wherein thevibration dampers extend across a mid-point of the elongated shaft andterminate prior to reaching the distal end.
 5. The sensor assembly ofclaim 1, wherein the spaced apart vibration dampers include a taperedportion at a distal end thereof.
 6. The sensor assembly of claim 1,wherein the vibration dampers are radially spaced apart about alongitudinal axis of the elongated shaft.
 7. The sensor assembly ofclaim 1, wherein the vibration dampers are only four rib members.
 8. Thesensor assembly of claim 1, wherein the vibration dampers are only sixrib members.
 9. The sensor assembly of claim 1, wherein the elongatedshaft has a length of about 80 mm.
 10. The sensor assembly of claim 1,wherein the elongated shaft has an outer diameter of about 3.0 mm at thedistal end, and an outer diameter of about 4.5 mm at the proximal endincluding the vibration dampers.
 11. The sensor assembly of claim 1,wherein the vibration dampers are evenly spaced apart.
 12. The sensorassembly of claim 1, wherein the sensor assembly is an exhaust gastemperature sensor assembly.
 13. The sensor assembly of claim 12,wherein the elongated shaft has a first mode of vibration of at least500 Hz.
 14. A sensor assembly including a sensing element, a conductorconnected to the sensing element, and an elongated shaft comprising: aproximal end; a distal end; an inner surface defining a throughboreextending from the proximal end to the distal end, the throughboreconfigured to receive the conductor therethrough; an outer surface; anda plurality of evenly spaced apart vibration dampers protruding from theouter surface and extending from the proximal end towards the distal endand terminating prior to reaching the distal end, the vibration dampersextending linearly and parallel to a longitudinal axis of the elongatedshaft; wherein the sensing element is configured to sense properties ofa gas.
 15. The sensor assembly of claim 14, wherein the vibrationdampers are only four rib members.
 16. The sensor assembly of claim 14,wherein the vibration dampers are only six rib members.
 17. A sensorassembly including a temperature sensing element, a conductor connectedto the temperature sensing element, and an elongated shaft comprising: aproximal end; a distal end; an inner surface defining a throughboreextending from the proximal end to the distal end, the throughboreconfigured to receive the conductor therethrough; an outer surface; andone of four or six vibration dampening ribs protruding from the outersurface that are evenly spaced apart radially about a longitudinal axisof the elongated shaft and extend linearly from the proximal endparallel to the longitudinal axis across a mid-point of the elongatedshaft and terminate prior to reaching the distal end; wherein thetemperature sensing element is an exhaust gas temperature sensingthermistor.
 18. The sensor assembly of claim 17, wherein the elongatedshaft has a length of about 80 mm, an outer diameter of about 3.0 mm atthe distal end, and an outer diameter of about 4.5 mm at the proximalend including the vibration dampening ribs.
 19. The sensor assembly ofclaim 17, wherein the elongated shaft has a first mode of vibration ofat least 500 Hz.